Glucose is the main fuel that powers your body. A healthy level is important for proper functioning of different organs especially the brain. Glucose is maintained at a relatively constant range to avoid health risks associated with persistently high blood levels. However, immediately after a meal, levels may temporarily rise as this balancing mechanism takes a while to take full effect. Blood glucose levels are measured in milligrams per deciliter or millimoles per liter of blood.
Before a meal
Normal levels of blood glucose range between 60 and 100 mg/dL. This levels are usually maintained by different mechanisms in the body. They may be affected by stress, exercise and some drugs. low levels are termed hypoglycemia and high levels are called hyperglycemia. Glucose levels after a fast are usually marginally lower than blood levels at other times.
1 hour after a meal
Blood glucose level rises after a meal because the body needs time to reduce glucose back to its normal range. The extent of this rise depends on the sugar content of each meal. For a meal containing about 75 g of glucose, blood glucose should be less than 200 mg/dL and less than 180 mg/dL for a 100 g meal. Readings above this level means the body is not handling glucose appropriately. Medically, this is termed impaired glucose tolerance.
2 hours after a meal
Two hours after a meal, glucose balancing mechanisms begin to get an upper hand and blood glucose begins to drop. At this time, blood glucose should have dropped to less than 140 md/dL and 155 mg/dL for 75 and 100 g glucose meals, respectively. Higher levels may suggest an impaired glucose lowering mechanism. Three hours after a meal, glucose levels should be below 140 mg/dL of blood for a 100 g glucose meal.
Glucose Tolerance
In order to screen patients with a impaired glucose metabolism, a doctor may perform a glucose tolerance test. This is frequently done for pregnant women or individuals suspected to have diabetes. You can also have a fasting or random blood glucose testing. These tests have different normal ranges and your doctor will decide which test is best for you. However, a blood glucose level above 200 for any glucose test is abnormal and should be further investigated.
References
- MedlinePlus: Glucose Tolerance Test
- MayoClinic.com; Glucose Tolerance Test
- Modern Nutrition in Health and Diseases; M.E. Shils; 2006
